The present invention relates to the treatement of by-products generated during the manufacture of methyl chlorosilanes. The basic process for the manufacture of such silane compounds is well known and is described in U.S. Pat. No. 2,380,995. Such a process generates by-products which at the present time have little or no commercial value. These by-products can present problems in their safe and environmentally acceptable ultimate disposal. The by-product streams of immediate interest are those consisting of high-boiling liquids (&gt;75.degree. C.); suspended silicon powder; elevated levels of copper, zinc and tin; as well as, a variety of other metals. Upon uncontrolled exposure to moisture and air, these materials may be easily ignited and/or form strong acid mists and liquid streams.
Procedures for the disposal of these by-products, and similar ones, are reported in U.S. Pat. Nos. 4,221,691; 4,408,030; 4,758,352; and 4,960,523; and in German patent DE3523541 A1.
U.S. Pat. No. 4,221,691 discloses a method of hydrolyzing polyfunctional chlorosilicon compositions which involves adding a hydrocarbon oil to the chlorosilicon composition, prior to hydrolysis in an aqueous medium containing concentrated HCl and/or CaCl.sub.2. Hydrolysis of the comparable streams from the methylchlorosilane process is also disclosed in U.S. Pat. No. 4,408,030. This process utilizes concentrated HCl to hydrolyze the waste stream containing silicon chlorides. The other patents disclose similar processes but do not address the reduction of the chloride content or the disposition of copper present in the original by-product stream.
There is thus a need to develop a better process that can reduce the chloride content from the hydrolyzed by-products to produce a solid material containing copper and other metals. Among other benefits, such a product has value as a source of copper for recovery. An effective process should produce a final passivated solid that has a high flash point, little or no gas evolution, non-sticky, free-flowing and non-dusting material that can be readily handled and transported.